Spanakopita ingredient (4)
I believe the answer is:
feta
'spanakopita ingredient' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for feta that I've seen before include "Greek sheep or goats' cheese" , "Greek salad cheese" , "Goat's or sheep's milk cheese" , "Greek dairy product" , "Greek cheese from goat or sheep milk" .)